Fig. 3From: Potential causal factors of CFS/ME: a concise and systematic scoping review of factors researchedStudies published per year, 1979–June 2019. *Published before June 2019. The number of studies published per year has increased steadily since the late 1980’s, with at least 48 studies published yearly 2015–2019, and 40 published in the first half of 2019Back to article page